Dealing with roundworms? Advice Needed!

I took my four kittens and Mixi into the vet yesterday. I brought in a kitten stool sample and apparently they have roundworms. They're 7 weeks old. I need to take my other kitty Shaggy in to get weighed and dewormed too as a precaution. He likes to lick their butts a lot, so I'm almost positive he has them too.

What I'm asking for is any advice to get rid of the worms for good. I have a second dose for Mixi and babies to give in two weeks. Should I completely change every litter box? And when? When should I have them tested for worms again to ensure they're all gone?

My vet said that roundworms are transferrable to humans, and I can't place a kitten into one home until they are absolutely all gone because she has a two year old.

I've never had to deal with worms, so please help!

So how long did the vet say it would be before they were all gone? I'm under the impression they are gone in one or two doses of worm medicine. Maybe call them back and ask.

Well, Shaggy, my 6 year old, has an appointment on Friday for a wellness check and worming. I'll ask then seeing as I have jury duty on Wednesday and Thursday